Centerless grinder

ABSTRACT

A fixture for converting a surface grinder or any machine having a grinding wheel and a support below said grinding wheel into a centerless grinder, said fixture including rotatably supported shaft means and a regulating roller mounted thereon for rotation therewith near the grinding wheel. The roller will usually rotate around an axis substantially parallel with the axis of rotation of the grinding wheel, but said roller axis may be transverse of the wheel axis. Guide means on said fixture position a workpiece between the grinding wheel and regulating roller for rotation and grinding thereby. Drive means are connected to the grinding wheel and the shaft means for effecting rotation thereof.

United States Patent [1 1 Mackay et al.

[ 1 CENTERLESS GRINDER [75] Inventors: John A. Mackay, Warren; John A.

Doran, III, Hartland, both of Mich.

[73] Assignee: Unison Corporation, Madison Heights, Mich.

[221 Filed: Nov. 9, 1970 [21] App1.No.: 87,779

[52] U.S.Cl. ..51/103 R,5l/241 R [51] Int. Cl. ..B24b 5/18 [58] Field ofSearch ..51/103 R, 241 R [56] References Cited UNITED STATES PATENTS1,264,129 4/1918 Reeves ..51/103 R X 1,452,508 4/1923 Hervig .l.,5l/l03R X 1,733,091 10/1929 H01mes.. ....51/103 R X 1,733,098 10/1929 Kern51/103 R 1,858,235 5/1932 Briney ..51/103 R X c I l 74 I I \t 1 3 [451Apr. 24, 1-973 Primary ExaminerHarold D. Whitehead Art0rney-Wo0dhams,Blanchard, and Flynn [57] ABSTRACT A fixture for converting a surfacegrinder or any machine having a grinding wheel and a support below saidgrinding wheel into a centerless grinder, said fixture includingrotatably supported shaft means and a regulating roller mounted thereonfor rotation therewith near the grinding wheel. The roller will usuallyrotate around an axis substantially parallel with the axis of rotationof the grinding wheel, but said roller axis may be transverse of thewheel axis. Guide means on said fixture position a workpiece between thegrinding wheel and regulating roller for rotation and grinding thereby.Drive means are connected to the grinding wheel and the shaft means foreffecting rotation thereof.

10 Claims, 9 Drawing Figures Patented. April 24, 1973 3,729,300

3 Sheets-Sheet 1 Patented April 24, 1973 3 Sheets-Sheet 2 Patented April24, 1973 3,729,300

3 Sheets-Sheet :3

CENTERLESS GRINDER FIELD OF THE INVENTION This invention relates ingeneral to a machine capable of performing a centerless grindingoperation and, more particularly, to a fixture capable of converting aconventional grinding machine having a grinding wheel into a centerlessgrinder.

BACKGROUND OF THE INVENTION The art of centerless grinding is well knownand many machines have been developed for this purpose. However, therehas been a long and recognized need for a fixture for quickly and easilyconverting a conventional surface grinder having a grinding wheel andworkpiece supporting means into a centerless grinder, especially capableof handling extremely small workpieces and capable of performing anextremely accurate grinding operation.

Previous efforts to provide an extremely accurate centerless grindingmachine capable of working on unusually small workpieces has beenfrustrated and limited by the accuracy of the shaft and bearing assemblysupporting the regulating roller which cooperates with the grindingwheel to perform the centerless grinding operation. More specifically,even a very small amount of axial or radial movement of the rollersupporting shaft can readily result in defective workpieces when closetolerances are required. Efforts to eliminate axial and radial play ofthe shaft relative to the frame structure supporting the shaft haveresulted in excessively expensive structures or in a bent shaft whichproduces a different type of inaccuracy. That is, it has been extremelydifficult, if not almost impossible, to provide a shaft which firmlyengages the bearings in an axial direction, in order to prevent axial orradial movement ofthe shaft, without at the same time imposing a bendingmoment on the shaft. Thus, when the engaging surfaces of the nut andbearing adjacent thereto are tightly drawn together by the nut, theresult has been a tendency to produce a bending moment in the shaft.More specifically, some form of external thread is required on existingshafts, for this purpose, to be engaged by a lock nut which imposes thethrust on the bearings. However, it has been impossible to furnishthreads on the shaft, much less on the nut, by conventional inexpensiveprocedures, which threads have a central axis coaxial with the shaft.

In the course of studying the foregoing problems, it was discovered thataxial and radial play could be eliminated without shaft deflection byproviding an improved shaft and bearing construction wherein the shafthas two parts which are slightly axially spaced from each other in theassembled condition. These two parts are interconnected by screw meanswhich extends substantially coaxially through one of the shaft parts andinto the other shaft part. This screw means is of relatively smalldiameter, by comparison with the shaft diameter, so that a lackofcoaxial relationship between its threads or the threads in the shaftmeans is incapable ofimposing a deflection of the shaft. Instead, thescrew means will deflect. Moreover, the screw means does not directlyengage the bearings, and the two parts of the shaft do not engage eachother whereby a deflection of the shaft means might be caused.

The spindle of the grinding machine may be furnished with theabove-described shaft and bearing assembly in order to eliminate axialmovement thereof without deflection therein. However, if axial movementof the regulating roller is eliminated, then the adverse affects fromthe capability of the spindle to move slightly axially are nullified.That is, the regulating roller acting through the workpiece will tend toprevent axial movement of the grinding wheel. Moreover, it is commonknowledge that the spindle of a grinding machine is usually supported bybearings arranged to minimize axial movement of the spindle shaft inorder to adapt the grinding wheel for special grinding operations otherthan centerless grinding, which the grinding machine is capable ofperforming by means of the fixture of this invention.

Accordingly, a primary object of this invention is the provision of afixture for converting into a centerless grinder a surface grindingmachine having a rotatable grinding wheel and a workpiece support nearsaid grinding wheel, whereby extremely small workpieces can be groundwith extreme accuracy.

A further object of this invention is the provision ofa fixture, asaforesaid, capable of relatively inexpensive manufacture whilemaintaining extreme accuracy in performance and compactness in size sothat said fixture can be quickly and easily mounted on the workpiecesupport ofa conventional grinding machine.

A further object of this invention is the provision of a centerlessgrinding machine having a regulating roller mounted upon a shaft andbearing assembly which is arranged and constructed so that axial andradial movement ofthe shaft is negligible, such being accomplishedwithout producing undesirable deflections in the shaft and without theneed for extremely accurate and costly machining operations on the partsof the fixture.

Other objects and purposes of this invention will become apparent topersons familiar with this type of equipment upon reading the followingdescriptive material and examining the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view ofaconventional surface grinding machine having a fixture constructedaccording to the present invention mounted thereon for converting sameinto a centerless grinding machine.

FIG. 2 is a perspective view of the fixture used for converting asurface grinder into a centerless grinder, the fixture being seensubstantially from the rearward side thereof.

FIG. 3 is a rear elevational view of said fixture.

FIG. 4 is a top view of said fixture with the workpiece and pressureroller removed for illustrative purposes.

FIG. 5 is a sectional view taken along the line V-V in FIG. 3.

FIG. 6 is a fragmentary sectional view taken along the line VIVI in FIG.4.

FIG. 7 is a fragmentary the line VllVIl in FIG. 3.

FIG. 8 schematically illustrates the coaction between the grindingwheel, the workpiece and the regulating roller when the grinding wheelis disposed directly above the regulating roller.

FIG. 9 is a schematic illustration of a further mode of operationwherein the grinding wheel is above, but axially offset from, theregulating roller.

sectional view taken along For convenience in description, the termsupper," lower, front, rear and words of similar import will havereference to the fixture of the invention and the grinding machine withwhich it isnormally associated as appearing in FIG. 2, which illustratesa rear view thereof. The terms inner, outer"and derivatives thereof willhave reference to the geometric center of the fixture, the associatedgrinding machine and parts thereof.

SUMMARY OF THE INVENTION The objects and purposes of the invention,including those set forth above, have been met by providing a fixturewhich is utilized to convert a conventional surface grinding machineinto a centerless grinding machine. The fixture includes a shaft andbearing means which supports a regulating roller beneath the grindingwheel so that the shaft of the fixture is parallel with and directlybelow the axis of the grinding machine spindle. The fixture includesguide means for positioning the workpiece in the space between theregulating roller and the grinding wheel. In this instance, the grindingwheel is driven by one prime mover and the roller sup porting shaft isdriven by another prime mover, but a single prime mover means iscontemplated.

DETAILED DESCRIPTION FIG. 1 illustrates therein a conventional surfacegrinding machine 11 provided with a frame 12 having a conventionalhorizontally extending spindle (not shown) rotatably supported thereon,which spindle is vertically movable and has a conventional grindingwheel 13 mounted thereon adjacent the forward end thereof. The frame 12is also provided with either a single or double slide thereon, themachine 11 as illustrated being provided with a double or cross-slidearrangement which includes a bottom slide 16 slidably supported on theframe E2. The linear movement of the bottom slide 16 is controlled by ahand wheel 17. A top slide 18 is slidably supported on the bottom slide16 and the linear movement thereof is controlled by a further hand wheel19. The slides 16 and 18 are mounted for slidable linear movement indirections transverse to one another and are additionally mounted formovement in directions which are parallel to and transverse to therotational axis of the grinding wheel spindle. The above structure isconventional and thus further description thereof is not believednecessary.

According to the present invention, the surface grinding machine 11 isprovided with a fixture 21 having a sine base 20 mounted on the uppertable 18 in the space between the table 18 and the grinding wheel 13.Said fixture 2] is designed to convert the surface grinding machine soas to permit performance ofa centerless grinding operation on acylindrical workpiece, such as workpiece W illustrated in FIG. 1.

The fixture 21, as illustrated in FIGS. 2 through 7, includes a pedestal22 which is adapted to be mounted upon the sine base 20 by means of thetwo cylindrical bars 23 and 23A. The bar 23 is pivotally connected tothe sine base 20,- and the bar 23A is movable vertically relative to thesine base 20.

The pedestal 22 is provided with an upstanding portion 25 adjacent thefront side thereof which rotatably supports a roller shaft means 24(FIG. The shaft means 24 is disposed for rotation about a horizontalaxis which is substantially'parallel with and vertically spaced belowthe rotational axis of the grinding wheel 13, but said shaft means canbe pivoted with the pedestal 22 around the axis of bar 23.

The shaft means 24 is of two-piece construction and specificallyincludes a first shaft segment 27 having a regulating roller 26nonrotatably secured upon one end thereof. The shaft segment 27 isrotatably supported by two pairs of conventional antifriction bearings28 and 29, which are separated by spacing sleeves 40 and 40A and whichare all disposed on one axial side of the regulating roller 26. Theshaft segment 27 is also provided with a conventional retaining ring 31secured thereto, which ring abuts the inner race of the antifrictionbearing 28 for restricting axial movement of shaft segment 27 in theforward (leftward in FIG. 5) direction.

The shaft segment 27 has a tapered end (FIG. 5) of conventionalconfiguration upon which an adapter 30 is rigidly secured by the nut 35for mounting the roller 26 on said segment 27. The roller 26 may befabricated from abrasive or nonabrasive materials, as desired. Byfurnishing a taper on shaft segment 27, the roller 26 can be quicklymounted upon the grinding wheel spindle for dressing of the roller at amuch higher rotational speed, particularly where profile grinding is tobe performed. This greatly reduces the time required to prepare theroller.

The shaft means 24 also includes a second shaft segment 32 which iscoaxially aligned with and disposed adjacent the other end of the shaftsegment 27. The adjacent surfaces of the shaft segments 27 and 32 areslightly spaced from one another so as to define a small clearance space33 therebetween, and a key or pin 36 extends between the shaft segments27 and 32 for holding said segments against relative rotation. A screw34 is coaxial with and interconnects the shaft segments 27 and 32, whichscrew results in total elimination of axial play of the shaft means 24by causing the stop ring 31 to abut against the inner race of theantifriction bearing 28, while at the same time causing the shoulder 39as formed on the shaft segment 32 to abut against the inner race of theantifriction bearing 29. This construction not only eliminates axialplay of the roller shaft means 24, but also prevents deflection ordistortion of the shaft means 24 due to the coaxial alignment of theconnecting screw 34 with the shaft segments. Moreover, since theadjacent surfaces of the segments 27 and 32 do not touch, it isunnecessary to accurately machine these surfaces in order to avoid ashaft deflection.

The shaft means 24 is indirectly driven by a conventional motor 41,which motor is drivingly connected to a conventional gear reducer 42mounted on the frame 22. The output shaft of the gear reducer 42 has adriving pulley 40 (FIG. 4) secured thereto, which pulley is inengagement with a driving belt 38. The shaft segment 32 has aconventional pulley 37 secured thereto, which pulley is in engagementwith and driven by the belt 38. The belt 38 and the pulleys associatedtherewith are preferably enclosed by a conventional shield or shroud 43.

The axis of the regulating roller 26, as disclosed in FIG. 8, isdisposed under the grinding wheel 13 whereby a workpiece W can bepositioned between and in engagement with the peripheries of theregulating roller 26 and grinding wheel 13 for permitting centerlessgrinding of the workpiece W. The axis of the workpiece W (FIGS. 8 and 9)may be slightly left or right (approximately one-eighth inch) of a lineconnecting the axes of the wheel 13 and roller 26 in order to achievespecific results.

To effect the centerless grinding of the workpiece W, the fixture 21 isprovided with guide structure for maintaining. the workpiece W in theregion between and in engagement with the regulating roller and thegrinding wheel. Specifically a blade support 44 (FIGS. 2 and 3) isadjustably mounted upon the upstanding portion 25 of the pedestal 22 anda'pressure roller device 46 (FIG. 2) is adapted for coaction with theworkpiece when the grinding wheel 13 and regulating roller 26 areaxially offset, as appearing in FIGS. 2 and 5.

The blade support 44 (FIGS. 2 and 3) is vertically slidably mounted onthe portion 25 of pedestal 22 by a pair of screws 48, which extendthrough vertically elongated slots 49 formed in the support 44. Thesupport 44 is guided for vertical slidingmovement relative to theportion 25 by means of a vertically extending guide or slide pin 51(FIG. 6).

The support 44 is provided with a rotatable adjustment member 52threadedly engaged therewith, which adjustment member 52 has its lowerend disposed in abutting engagement with an upwardly facing surface orshoulder 53 formed on the pedestal 22. The upper end of adjustmentmember 52 is disposed in a slot 54 formed in the support 44 forpermitting the adjustment member 52 to be engaged by a conventional toolfor selected rotation of the adjustment member 52, which in turn causesa selected vertical movement of the support 44 relative to the pedestal22.

The blade support 44 has a substantially horizontal blade 56 mounted onthe upper surface thereof. The blade 56 is adjustably secured to thesupport 44 by means of screws 57, which extend through elongated slots58 formed in the blade 56 for permitting the blade to be adjustedlinearly in a horizontal direction which is substantially transverse tothe rotational axis of the regulating roller 26 for permitting thebeveled edge 59 of the blade 56 to be moved into engagement with theperiphery of the workpiece W. i

The pressure roller device 46 includes a pressure roller 61 adapted tobe disposed in rolling engagement with the periphery of the workpiece W.The pressure roller 61 is rotatably supported adjacent one end of an arm62, which arm is releasably but firmly secured to a block 63. The block63 is nonrotatably connected to a pivot shaft 64 which is rotatablysupported on the portion 25 of pedestal 22. A torsion spring 66 (FIG. 7)is disposed in surrounding relationship to one end of the pivot shaft 64and has the opposite ends thereof anchored to the'pivot shaft 64 and thepedestal 22 for normally urging the pivot shaft 64 to rotate in adirection (clockwise in FIG. 3) which will cause the pressure roller 61to be resiliently urged into engagement with the workpiece W.

A control handle 67, which is threaded and fixedly secured to the block63, extends outwardly from the block for permitting the pivot shaft 64and arm 62 to be selectively moved around the axis of shaft 64. Thelower end of control handle 67 extends through an elongated slot 68formed in the arm 62, which slot permits the arm 62 to be selectivelymoved relative to the block 63 so as to selectively vary the radialspacing of the pressure roller 61 from the axis of the pivot shaft 64.The arm 62 is releasably locked relative to the block 63 by means of alock nut 69 provided on the control handle 67.

The pressure roller 61 (FIG. 4) may be canted slightly, such as 3, sothat it automatically urges axial movement of the workpiece W toward (oraway from) the positioning member 74.

The fixture 21 is also provided with a workpiece positioning device 71(FIGS. 2 and 4), which device includes an arm 72 releasably connected tothe pedestal 22 by means of a, screw 73, which screw permits the arm 72to be adjusted angularly around the axis of the screw 73 for enablingthe arm to be located in a selected angular position. An elongatedpositioning member 74 is supported on, and extends through an openingprovided adjacent the free end of, the arm 72. Said positioning memberis provided with a contact element 76 adjacent the rear end thereof,which element is adapted to engage the front axial end face of theworkpiece W adjacent the center thereof. The elongated positioningmember 74 is slidably supported by the arm 72 and is releasably securedto said arm in a selected position by means ofa locking screw 77.

The workpiece positioning device can also be mounted the front side ofthe blade support 44 by means of a rod (not shown) which is insertedinto the opening 78 and to which the screw 73 is then attached. In thismanner the device 71 is used to engage the other end of the workpiece.

The fixture 21 is also provided with a suitable nozzle member 79, whichis connected to suitable lubricant or fluid supply conduits and has adischarge end positioned adjacent the workpiece for permitting theworkpiece to be sprayed with a suitable lubricant and/or coolant.

When the fixture 21 is used in the manner disclosed in FIGS. 1 and 8,namely, with the wheel 13 and oller 26 in radially opposed positions,then an infeed device 81 is useful. Specifically, a bracket 82 ismounted upon the block 63 and adjustably supports an infeed finger 83.The workpiece W is engaged by the flat end of the finger 83 on the sidethereof opposite the side engaged by the blade56.

OPERATION In utilization of the fixture 21 in cooperation with 'aconventional surface grinder 11 for permitting centerless grinding ofcylindrical workpieces, the fixture 21 is mounted upon the sine base 20which is secured upon the upper movable table 18 so that the regulatingroller 26 may be disposed for rotation about a horizontal axissubstantially parallel with and disposed below the rotational axis ofthe grinding wheel 13. However, the axis of the roller 26 may be tiltedwith the pedestal 22 around the axis of bar 23. The regulating roller 26and grinding wheel 13 are spaced apart a sufficient distance to permit asuitable workpiece W to be engaged therebetween in the mannerillustrated either in FIG. 1 or in FIG. 2. For purposes of illustrationand explanation of the present invention, the workpiece W is shown ashaving two portions of different diameters, the large portion W1 (FIG.5) being disposed directly on the regulating roller 26 and the otherportion W2 projecting outwardly from the regulating roller. The portionW2 may have a diameter either less than orgreater than the portion W1.

Assuming first that it is desired to perform a centerless grindingoperation on the workpiece portion W1, then the table 18 with thefixture 21 will be positioned so that the regulating roller 26 isdisposed beneath the grinding wheel 13, whereupon the cylindricalworkpiece portion Wl will be contacted on substantially diametricallyopposite sides thereof by the grinding wheel 13 and the regulatingroller 26, substantially as illustrated in FIG. 8. The blade 56 will beadjusted both vertically and horizontally so that the beveled edge 59 ofthe blade (FIG. 6) will be in tangential engagement with the peripheryof the workpiece portion W1. Also, the infeed finger 83 (FIG. 8) will beadjusted into engagement with the opposite side of the workpiece. Theworkpiece portion W1 will thus be engaged at four points.

In this mode of operation, the pressure roller 61 and its arm 62 willnormally be removed from the block 63 (FIG. 8) and replaced by infeeddevice 81. When in the position illustrated in FIG. 8, the grindingwheel 13 will be rotated in the direction illustrated by the arrow andwill normally rotate at a much faster peripheral speed than theregulating roller so that the workpiece W will be continually rolledinto engagement with the guide blade 56.

When it is desired to grind the projecting portion W2 of the workpiece,the table 18 and the fixture 21 mounted thereon will be movedfrontwardly relative to the grinding wheel whereupon the grinding wheeland regulating roller will thus be axially offset from each other. Whenin this position, the workpiece portion W1 will be in contact with theregulating roller 26 and the blade 56, but the infeed finger 83 will beremoved. The pressure roller arm 62 will be mounted in the operativeposition on block 63 (FIG. 2) so that the pressure roller 61 will beresiliently urged into rolling engagement with the'periphery of theworkpiece portion W1. The pressure roller 61, blade 62 and regulatingroller 26 thus provide a three-point support for the workpiece W,whereupon the grinding wheel 13 can then be moved downwardly intogrinding engagement with the projecting portion W2 (FIG. 9) to perform acenterless grinding operation thereon, which operation will produce anaccurately coaxial diameter.

The device constructed according to the present invention is thusoperable for centerless grinding of members having portions disposeddirectly above or projecting laterally outwardly from the regulatingroller, and is also adaptable for grinding members having sizes rangingfrom very small to relatively large diameters due to the manner in whichthe workpiece is disposed between the grinding wheel and the regulatingroller.

Further, extremely accurate centerless grinding of the workpiece ispossible with the fixture according to the present invention, eventhough the regulating roller. 26 is mounted adjacent one end of theshaft means 24, due to the manner in which the shaft is supported so asto be free of inherent axial play and lateral deflection, therebypermitting the centerless grinding of the workpiece with a high degreeof precision.

Although particular preferred embodiments of the invention hasbeendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of-the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a grinding machine having a grinding wheel having a firstrotational axis and support means spaced from said grinding wheel, afixture for converting said grinding machine to a centerless grinder,comprising:

base means mounted upon said support means;

shaft means having a second rotational axis, said shaft means beingrotatably supported upon said base means and adapted to be positionedwith said second axis substantially coplanar with said first axis;

bearing means mounted on said base means and rotatably supporting saidshaft means;

said shaft means having separate, axially spaced, front and rear partsengaged by said bearing means, and threaded means coaxial with saidshaft means and connecting said front and rear parts together;

a regulating roller mounted upon said shaft means near one end thereoffor rotation therewith, said regulating roller being adapted for radialalignment with said grinding wheel;

drive means mounted upon said base means and connected to said shaftmeans near the other end thereof for rotating said shaft means; and

guide means mounted upon said base means for positioning a workpiece inengagement with said grinding wheel and said regulating roller, wherebysaid workpiece can be rotated and ground between said grinding wheel andsaid regulating roller.

2. A grinding machine according to claim 1 wherein said regulatingroller is located in a position axially offset from said grinding wheel.

3. A grinding machine according to claim 1, wherein said bearing meanscomprises front and rear, axially spaced antifriction bearings, one ofsaid bearings having inner race means and one of said shaft parts have aportion of enlarged diameter defining a shoulder engaged with said innerrace means.

4. A grinding machine according to claim 1, wherein said bearing meanscomprises first and second, axially spaced antifriction bearingsdisposed adjacent and in surrounding relationship to the front and rearparts of the shaft means, respectively, said front and rear antifrictionbearings being disposed on one axial side of said regulating roller,said front and rear parts of said shaft means having opposed end faceswhich are disposed adjacent but spaced from one another, and said frontand rear parts further each having an abutment shoulder thereon fixedlysecured thereto and disposed in abutting contact with the inner race ofthe front and rear bearings. respectively, for preventing axial play ormovement of the shaft means.

5. A centerless grinding attachment for use with a grinder having a worktable and a grinding wheel disposed above the work table and mounted forrotation about a first substantially horizontal rotational axis,comprising:

base means adapted to be supported on the work table;

shaft means having a second rotational axis, said shaft means beingrotatably supported on said base means and adapted to be positioned sothat said second rotational axis is substantially coplanar with andspaced downwardly from the first rotational axis of the grinding wheel;

a regulation roller secured to and rotatable with said shaft meansadjacent one free end thereof, said regulating roller being adapted tobe disposed below and substantially radially aligned with said grindingwheel;

bearing means coacting between said base means and said shaft means forrotatably supporting said shaft means on said base means, said bearingmeans being entirely disposed on one axial side of said regulatingroller for supporting said regulating roller in a cantilever manner;

driving means connected to said regulating roller for driving same;

first guide means including a blade adjustably mounted on said basemeans and disposed substantially within a plane passing between saidregulating roller and said grinding wheel for engagement with acylindrical workpiece bearing against said regulating roller;

adjustment means on said first guide means coacting with said blade andwith said base means for selectively effecting vertical and horizontalmovement ofsaid blade relative to said regulating roller; and

second guide means including spring-urged roller means mounted on saidbase means and adapted for engagement with the cylindrical workpiece ina region thereof which is angularly displaced from the engagementbetween said blade and said workpiece.

6. An attachment according to claim 5, wherein said shaft means has atapered portion near said one free end and said regulating roller has atapered bore into which said tapered portion is snugly receivable, andscrew means securing said roller on said shaft means.

7. An attachment according to claim 5, wherein said spring urged rollermeans is disposed for engagement with the cylindrical workpiece in aregion thereof located above the axis of the workpiece.

8. An attachment according to claim 7, wherein said spring-urged rollermeans is canted at a slight angle relative to the regulating roller sothat rotation of said spring-urged roller means while engaging saidworkpiece effects an axial urging thereof.

9. An attachment according to claim 7, wherein said shaft means includesfirst and second, axially aligned and axially spaced shaft segmentshaving adjacent faces which are spaced from each other, said regulatingroller being secured to and rotatable with said first shaft segmentadjacent the free end thereof, said second shaft segment being connectedto and driven by said driving means, and threaded fastener meanscoaxially aligned with and fixedly interconnecting said first and secondshaft segments.

10. A centerless grinding attachment for use with a grinder having awork table and a grinding wheel disposed above the work table andmounted for rotation about a first substantially horizontal rotationalaxis, comprising:

base means adapted to be supported on the work table;

shaft means having a second rotational axis, said shaft means beingrotatably supported upon said base means and adapted to be positionedwith said second axis substantially coplanar with said first axis;

a regulating roller mounted upon said shaft means near one end thereoffor rotation therewith, said regulating roller being adapted for radialalignment with said grinding wheel;

drive means mounted upon said base means and connected to said shaftmeans near the other end thereof for rotating said shaft means;

first guide means including a blade movably mounted on said base meansand disposed for engagement with a cylindrical workpiece bearing againstsaid regulating roller, said blade engaging said workpiece in a firstregion thereof located between the regions where said workpiece iscontracted by said grinding wheel and said regulating roller;

said first guide means including adjustment means coacting with saidblade for selectively effecting movement of said blade relative to saidbase means and relative to said regulating roller for permitting saidblade to engage said cylindrical workpiece; and

second guide means mounted on said base means and engaging saidcylindrical workpiece in a second region which is angularly displacedfrom all of said previously mentioned regions, said second guide meansincluding roller means engaging said workpiece at said second region,means mounting said roller means for movement thereof relative to saidbase means in a substantially lateral direction relative to the axis ofsaid roller means, and spring means normally resiliently urging saidroller means into engagement with said workpiece.

1. In a grinding machine having a grinding wheel having a firstrotational axis and support means spaced from said grinding wheel, afixture for converting said grinding machine to a centerless grinder,comprising: base means mounted upon said support means; shaft meanshaving a second rotational axis, said shaft means being rotatablysupported upon said base means and adapted to be positioned with saidsecond axis substantially coplanar with said first axis; bearing meansmounted on said base means and rotatably supporting said shaft means;said shaft means having separate, axially spaced, front and rear partsengaged by said bearing means, and threaded means coaxial with saidshaft means and connecting said front and rear parts together; aregulating roller mounted upon said shaft means near one end thereof forrotation therewith, said regulating roller being adapted for radialalignment with said grinding wheel; drive means mounted upon said basemeans and connected to said shaft means near the other end thereof forrotating said shaft means; and guide means mounted upon said base meansfor positioning a workpiece in engagement with said grinding wheel andsaid regulating roller, whereby said workpiece can be rotated and groundbetween said grinding wheel and said regulating roller.
 2. A grindingmachine according to claim 1 wherein said regulating roller is locatedin a position axially offset from said grinding wheel.
 3. A grindingmachine according to claim 1, wherein said bearing means comprises frontand rear, axially spaced antifriction bearings, one of said bearingshaving inner race means and one of said shaft parts have a portion ofenlarged diameter defining a shoulder engaged with said inner racemeans.
 4. A grinding machine according to claim 1, wherein said bearingmeans comprises first and second, axially spaced antifriction bearingsdisposed adjacent and in surrounding relationship to the front and rearparts of the shaft means, respectively, said front and rear antifrictionbearings being disposed on one axial side of said regulating roller,said front and rear parts of said shaft having opposed end faces whichare disposed adjacent but spaced from one another, and said front andrear parts further each having an abutment shoulder thereon fixedlysecured thereto and disposed in abutting contact with the inner race ofthe front and rear bearings, respectively, for preventing axial play ormovement of the shaft means.
 5. A centerless grinding attachment for usewith a grinder having a work table and a grinding wheel disposed abovethe work table and mounted for rotation about a first substantiallyhorizontal rotational axis, comprising: base means adapted to besupported on the work table; shaft means having a second rotationalaxis, said shaft means being rotatably supported on said base means andadapted to be positioned so that said second rotational axis issubstantially coplanar with and spaced downwardly from the firstrotational axis of the grinding wheel; a regulation roller secured toand rotatable with said shaft means aDjacent one free end thereof, saidregulating roller being adapted to be disposed below and substantiallyradially aligned with said grinding wheel; bearing means coactingbetween said base means and said shaft means for rotatably supportingsaid shaft means on said base means, said bearing means being entirelydisposed on one axial side of said regulating roller for supporting saidregulating roller in a cantilever manner; driving means connected tosaid regulating roller for driving same; first guide means including ablade adjustably mounted on said base means and disposed substantiallywithin a plane passing between said regulating roller and said grindingwheel for engagement with a cylindrical workpiece bearing against saidregulating roller; adjustment means on said first guide means coactingwith said blade and with said base means for selectively effectingvertical and horizontal movement of said blade relative to saidregulating roller; and second guide means including spring-urged rollermeans mounted on said base means and adapted for engagement with thecylindrical workpiece in a region thereof which is angularly displacedfrom the engagement between said blade and said workpiece.
 6. Anattachment according to claim 5, wherein said shaft means has a taperedportion near said one free end and said regulating roller has a taperedbore into which said tapered portion is snugly receivable, and screwmeans securing said roller on said shaft means.
 7. An attachmentaccording to claim 5, wherein said spring urged roller means is disposedfor engagement with the cylindrical workpiece in a region thereoflocated above the axis of the workpiece.
 8. An attachment according toclaim 7, wherein said spring-urged roller means is canted at a slightangle relative to the regulating roller so that rotation of saidspring-urged roller means while engaging said workpiece effects an axialurging thereof.
 9. An attachment according to claim 7, wherein saidshaft means includes first and second, axially aligned and axiallyspaced shaft segments having adjacent faces which are spaced from eachother, said regulating roller being secured to and rotatable with saidfirst shaft segment adjacent the free end thereof, said second shaftsegment being connected to and driven by said driving means, andthreaded fastener means coaxially aligned with and fixedlyinterconnecting said first and second shaft segments.
 10. A centerlessgrinding attachment for use with a grinder having a work table and agrinding wheel disposed above the work table and mounted for rotationabout a first substantially horizontal rotational axis, comprising: basemeans adapted to be supported on the work table; shaft means having asecond rotational axis, said shaft means being rotatably supported uponsaid base means and adapted to be positioned with said second axissubstantially coplanar with said first axis; a regulating roller mountedupon said shaft means near one end thereof for rotation therewith, saidregulating roller being adapted for radial alignment with said grindingwheel; drive means mounted upon said base means and connected to saidshaft means near the other end thereof for rotating said shaft means;first guide means including a blade movably mounted on said base meansand disposed for engagement with a cylindrical workpiece bearing againstsaid regulating roller, said blade engaging said workpiece in a firstregion thereof located between the regions where said workpiece iscontracted by said grinding wheel and said regulating roller; said firstguide means including adjustment means coacting with said blade forselectively effecting movement of said blade relative to said base meansand relative to said regulating roller for permitting said blade toengage said cylindrical workpiece; and second guide means mounted onsaid base means and engaging said cylindrical workpiece in a secondregion which is angularly displaced from all of said pReviouslymentioned regions, said second guide means including roller meansengaging said workpiece at said second region, means mounting saidroller means for movement thereof relative to said base means in asubstantially lateral direction relative to the axis of said rollermeans, and spring means normally resiliently urging said roller meansinto engagement with said workpiece.